1. Field of the Invention
This invention relates to the stabilization of photographic elements against fog and, more particularly, to photographic elements and emulsions containing a fog stabilizing amount of a glucoside humectant.
2. Description of the Prior Art
It is well known that the photosensitive emulsions of photographic film units storage tend to "fog", i.e., become spontaneously developable without light exposure. While fog increases with the degree of development of any given emulsion, with constant development conditions fog tends to increase with time and temperature. It is, of course, desirable to have emulsions as stable as possible under conditions of prolonged storage and high temperature, and hence many antifoggants and stabilizers have been proposed in the art as emulsion addenda to protect, to some extent, against the effects of such conditions.
Various polyhydric alcohols have been described as effectively reducing the formation of fog when added to emulsions as antifoggants, for example, the 1,2-glycols of Sonada et al, U.S. Pat. No. 3,650,759, and the polyhydroxy carboxylic acid derivatives of Humphlett, U.S. Pat. No. 3,396,028. It has also been proposed that plasticizers such as glycerine, ethylene glycol and certain other polyols, when added to silver halide emulsions, may result in the reduction of fog, particularly fog caused by mechanical stress. See, for example, Milton et al, U.S. Pat. No. 2,960,404; Albus et al, U.S. Pat. No. 3,042,524; and Nishio et al, U.S. Pat. No. 3,520,694.
Humectants such as glycerine and alpha methyl glucoside have been described, for example, in Farney, U.S. Pat. No. 3,666,460 as being effective in lowering the processing time and/or the amount of processing composition necessary to form an image in a silver diffusion transfer film unit. However, the superior fog-stabilizing effect of a glucoside humectant in a film unit for forming color images by diffusion transfer has heretofore been unknown and unanticipated.